The European Parliament's Brexit negotiator, Guy Verhofstadt, has rejected the UK's proposals for the border between Northern Ireland and the Republic of Ireland.
Speaking inside the Irish Parliament on Thursday morning, Mr. Verhofstadt said the proposals put forward by the British government are not possible.
"I have always thought that if a border is not visible, then it is no border," said Mr. Verhofstadt.
Mr. Verhofstadt went on to accuse the British government of not taking seriously the impact Brexit will have on the Good Friday Agreement.
"You can count on the European Parliament to defend the integrity of the Good Friday Agreement in all its parts."
Mr. Verhofstadt visited the Northern Ireland on Wednesday.
Last month, the British government said it would seek a number of waivers for goods (i.e. small traders and farmers) and people crossing the border.
The British government also said it wanted to avoid a return to any 'hard border'.